police that she did indeed kill him. she's claiming it was self-defense. but today, explosive new tapes reminded the jury that that was not always her story. here's abc's ryan owens. >> if travis were here today, he would tell you that it wasn't me. r >> reporter: her web of lies untangles before our lies. >> i'm all for the ten commandments. thou shalt not kill. >> reporter: every detail shown to riveted jurors, who will decide if jodi arias should die for her crime. >> if i hurt travis, if i killed travis, i would beg for the death penalty. >> reporter: for the last three days, the prosecutor has played interrogation videos of arias from july of 2008. she's just been arrested for the brutal murder of alexander. >> i'm begging you to at least come clean and tell me why. >> i wish that i had answers. i'm sorry. >> reporter: he was found butchered in the somehhower of home. >> if i was trying to kill somebody, i would use gloves. i have plenty of them. >> reporter: the 30-year-old businessman and devout mormon had been stabbed 27 times. his throat slit so deep he was almost de ceglcapita

drugs. my best defense is i've never tested positive. >> reporter: he didn't just lie to reporters, fans, sponsors, and even cancer survivors, he lied under oath, too. >> how many times do i have to say it? >> i just want to make sure your testimony is clear. >> if it can't be any clearer that i've never taken drugs. >> reporter: along way, armstrong's great lie left a trail of human collateral damage. people who went from friend to enemy the minute they threatened to expose him. >> it's a long time coming. i think it's a huge steph. >> reporter: frankie andreu was his best friend and teammate until he and his wife testified they heard him admit he took drugs. armstrong went on the attack, accusing frankie and betsy of lying. >> she said in her deposition she hates me. >> reporter: why would he say the same thing if you don't? >> probably to support his wife. >> reporter: after that, frankie went from friend to pariah almost overnight. >> i'd go to events and i didn't know who my friend was, who my foe was, who would shake my hand, who would spit at me in disgust. i got e-mails, tr